1. Field of the Invention
The invention relates to a method for the application of mortar or concrete by spraying, wherein a quick-acting binding agent, particularly a "short" cement mixed with an admixture is transferred to a spraying-nozzle by means of a pneumatic conveyor when water is added. The invention also relates to a device to carry out this method. The pneumatic conveyor transfers and simultaneously mixes the binding agent and the admixture.
2. Description of Related Art
The known method is primarily used for the restoration of concrete, such as in tunnels, bridges etc. Most of the time when compared with plaster and other finishing mortars the concrete must be applied in a somewhat thicker layer, which due to its heavy additives tends to drop before completely setting up. To avoid this, a quick-binding cement with additives which increases the viscosity of the not-set concrete is used. The commonly used addition of water-glass for the increase of viscosity could cause damage to the concrete later. In order to avoid this, extremely quick-binding cements which require a processing time of only a few seconds were used recently. In order for the cements not to bind during the mixing with the moisture of the admixture, dried sand and gravel are used, however at relatively high cost for the drying.
The purpose of this invention is to reduce the costs for the application of mortar or concrete with quick-acting binding agents by using a pneumatic conveyor to simultaneously mix and transfer the mortar or concrete prior the application.